If your site is live, the original-named files will remain on your web server. You could reset your webspace (but bear in mind that any links would break from external sites when the old pages go away) and use the File menu -> Re-Publish All Files once you’ve renamed the folders that the pages are in.

Ok thanks for your quick response. My site is live. I understand that links will be broken.

A related question, is there any tool/plugin to redirect any subdomain to the homepage? So that visitors to previous subdomains don’t get 404 errors? My site has a lot of subdomains so it would be difficult to do them individually.